Retro Amp 50W Single Supply

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#81
 
#82
lyubcho88 said:
Hi All,

Here is my pcb version on AX6 amplifier circuit with TO246 package power transistors.
https://www.dropbox.com/s/kz2m72offvtio1g/Board_TO246.GIF
PCB for print
https://www.dropbox.com/s/plh3ma156q8g0ug/AX6%20rev_1_6_TO246_PCB_PRINT.pdf
Schematic and Simulation
https://www.dropbox.com/s/f4c109ep479b6aw/sch1.png
https://www.dropbox.com/s/suvoupxhxv0yqtf/sch2.png
https://www.dropbox.com/s/szavhehgng9uhxh/sch3.png

The trimmers on bias and offset are these - https://www.dropbox.com/s/fk05m8ruosaaq9w/SH655MCL _trimers.pdf or Bourns

BR,
Lyubo
Click to expand...

Your outputs wrong connect, some pins reverted.
 
#83
Hello apexaudio!

I have a small question about this amplifier (AX6).
It may be appropriate for a bass guitar amplifier?
The power can be increased by making it four output transistors?

Regards!

PS: I regularly read your very interesting thread. 😉
 
#88

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#91
The AX6 with the improvements, an idle bias current setting potentiometer, and a center level symmetry improving potentiometer, is beginning to be useful.
I own an original dynaco ST120. With an original 5 digit RCA TO3 transistor on the PC14 (power supply regulator PWB), it will actually collapse the upper rail voltage if the current out gets above 6.25 Amps (as designed). It collapses the voltage at about 2.5 A with an NTE60 transistor, which has higher gain. All this is fine at a stable temperature, which I encourage with two PCAT fans blowing on the amp- 17 hours a day in most cases. Mine doesn't regulate at 72v, running more like 80 all the time. I don't hear hum, with a shorted input, so I don't worry about the regulation. My speakers are 101 db @ 1W ! m, fairly sensitive.
I think Salas G amp power supply is probably more useful, but no board layouts are available for it. http://www.diyaudio.com/forums/solid-state/229120-g-amp.html
I've bought the parts but have been doing other things, haven't actually built the G amp yet. I haven't been able to keep a *****se made printer cartridge running more than 6 weeks and 40 pages since 1998, so if I build anything it will be point to point on perf board.
With improved heat sinks, 2 fans blowing on the heat sinks, 80 v rail, and NTE60MP output transistors, the ST120 can put out much more than 60 w/ch into 8 ohm for a little while. Not long enough to play guitar on stage though. My average voltage out into 8 ohms is 1.5 Vpp, with 60 db higher peaks as the music reaches its climax.
 
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#95
djoffe said:
using the same source, e.g. Wikipedia, the Stereo 120 dates from 1966...
Click to expand...

Quite possible that they used an example from the RCA manual, or from a Wireless World article. Lots of ideas were shared via WW back then. Have a look at Peter Walker's Current Dumping amp article, which became the QUAD 405, then later the remarkably similar Stasis amps.
 
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